Effects of reverberation on loudness perception

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Department of Psychology

20 April 2023

Effects of reverberation on loudness perceptionAndrew Raimond

Effect of reverberation on loudness perception 2

Overview

• Previous Experiments– Pilot; Real-room reverberation; Mono v Dichotic.

• Current Experiments– Time order effects– Effects of frequency bands

Effect of reverberation on loudness perception

Loudness asymmetry

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Time

Am

plitu

de

Damped Sound

Ramped Sound

Damped

RampedAttack

Decay

Atta

ck

Decay


Loudness context effect

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• Which is loudest?

Time

Ramped Ramped

Damped Damped

Damped Ramped

Ramped Damped


Reverberation

• The “tails” on damped stimuli resemble effects of room reflections (Stecker & Hafter, 2000; Watkins, 2005).

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Dry speech

Reverberated speech

Dry Speech

Reverberant Speech


Loudness judgement

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Questions

• Perceived reduction in loudness of damped stimuli relative to ramped stimuli– is this still apparent with sounds that have tails processed from real-

room reflections?

• The loudness context effect– is this still apparent with sounds that have tails processed from real-

room reflections?

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Real-room reverberation

• However, tails added by real-room reverberation differ from the envelopes used by Stecker & Hafter:

- Real-room decays are not smooth

- Durations of real-room decays are usually longer

- Room-reflections de-correlate the signal at the two ears

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Left Channel

Right Channel


Experiment 1: Real-room

• Can real-room reverberation over-ride artificial shaping used by Stecker & Hafter?

• Perceived reduction in loudness of damped stimuli relative to ramped stimuli?

• The loudness context effect?

– Loudness asymmetry– Loudness context effect– Convolution with real-room reverberation overrides shaping used by

Stecker & Hafter.– Effects of real-room reflections are more substantial than shaping used by

Stecker & Hafter

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Experiment 2: Monaural v Dichotic

• Certain room-reflection ‘tail effects’ that have been found in speech perception experiments are increased in monaural conditions (Watkins, 2005).

• Is the loudness context effect also increased when sounds are presented in monaural real-room reverberation?

– Loudness asymmetry– Loudness context effect

– Effects of the real-room tails successfully oppose effects of the function-shaped tails, as there was a substantial context effect that depended on the direction of the real-room tail.

– As with ‘tail effects’ in speech, this context effect is found in both monaural and dichotic conditions, but is less prominent in dichotic conditions .

– There appears to be a ‘de-reverberation’ in dichotic conditions that may be due to the de-correlation between the two ears’ signals with the real-room BRIRs

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Damped-Ramped

Ramped-Damped

Ramped-Ramped

Damped-Damped

1700 ms

1350 ms

1350 ms

1000 ms

(Loudest)

(Least loud)

Experiment 3: Time order effects

Time

500 ms ISI



Ramped- Ramped

850 ms

Damped- Damped

850 ms

Peak-to-Peak 1700 ms

Damped- Ramped

500 ms

Ramped- Damped

1200 ms

850 ms


• 2IC task.

• Pure tones of equal power (330 Hz, 250 ms).

• Gated with either Ramped or Damped envelope, convolved with real-room 2.5 m BRIRs.

• Played through left channel.

• Standard stimulus (80 dB SPL), then ISI of 500,850,1200 or 1550 ms

• Then Test stimulus (selected at random from 70,72,.., 90 dB SPL)

• Which is loudest?

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Damped Test

Experiment 3: Results

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500 ms ISI

70 82 907874 86 70 82 907874 86

1

0

.5

Pro

port

ion

Tes

t > S

tand

ard

resp

onse

s

Test level (dB SPL)

Ramped Standard Damped Standard

Ramped Test

P.S.E

P.S.E


Damped Test

Ramped Test


15

850 ms ISI

70 82 907874 86 70 82 907874 86

1

0

.5

Pro

port

ion

Tes

t > S

tand

ard

resp

onse

s

Test level (dB SPL)


P.S.E

P.S.E


Damped Test

Ramped Test


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1200 ms ISI

70 82 907874 86 70 82 907874 86

1

0

.5

Pro

port

ion

Tes

t > S

tand

ard

resp

onse

s

Test level (dB SPL)


P.S.E

P.S.E


Damped Test

Ramped Test


17

1550 ms ISI

70 82 907874 86 70 82 907874 86

1

0

.5

Pro

port

ion

Tes

t > S

tand

ard

resp

onse

s

Test level (dB SPL)


P.S.E

P.S.E


Experiment 3: Pooled Results

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Ramped Damped

850 ms ISI500 ms ISI

Tot

al P

ropo

rtio

n T

est >

Sta

ndar

d R

espo

nses

Ramped Test

Damped Test

Standard Type

Ramped Damped

0.5

0.7

0.3

0.9

0.5

0.7

0.3

0.9


Experiment 3: Pooled Results

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Ramped Damped

1550 ms ISI1200 ms ISI

Tot

al P

ropo

rtio

n T

est >

Sta

ndar

d R

espo

nses

Ramped Test

Damped Test

Standard Type

Ramped Damped

0.5

0.7

0.3

0.9

0.5

0.7

0.3

0.9


70 82 907874 86

1

0

.5

Pro

port

ion

Tes

t > S

tand

ard

resp

onse

s

Damp test 850 ms ISI

Ramp test 500 ms ISI


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Equal Peak-to-Peak Times

Test level (dB SPL)

P.S.E

Damp test 1200ms ISI

Ramp test 850ms ISI

70 82 907874 86

Damped StandardRamped Standard

P.S.E


Experiment 3: Conclusions

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• Loudness asymmetry and loudness context effect are not dependant on Peak-to-Peak distance.

• While still able to make loudness judgments, loudness asymmetry disappears with ISIs longer than 850 ms.Thus, loudness context effect does so too.

• However, standard only contains one 300 ms reverberant tail, in one frequency region. Wideband (speech) contexts contain many more reverberant tails.


Experiment 4:

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• Ongoing experiments: Effects of frequency bands


Experiment 4: Effects of frequency bands

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• Perceptual constancy for reverberation is more effective within wideband sounds (Watkins & Makin, 2007).

• Perceptual mechanism seems to operate on a band-by-band basis.

• Test and standards used in Stecker & Hafter and in previous experiments have all occupied the same narrowband frequency region (300-Hz).

• Use standards and test sounds in different frequency bands to examine loudness asymmetry

• Investigate if loudness context effects are still apparent with cross-band standards and test sounds.


Thanks

Thank you!

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Effects of reverberation on loudness perception

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